PHP Programming with MySQL Slide 6-1 CHAPTER 6 Working with Files and Directories.

transcript

PHP Programming with MySQL Slide 6-1

CHAPTER 6Working with Files

and Directories

Objectives

Open and close files Write data to files Read data from files Manage files and directories

Opening and Closing File Streams

A stream is a channel used for accessing a resource that you can read from and write to

The input stream reads data from a resource (such as a file)

The output stream writes data to a resource

1. Open the file stream with the fopen() function

2. Write data to or read data from the file stream

3. Close the file stream with the fclose() function

Opening a File Stream

A handle is a special type of variable that PHP uses to represent a resource such as a file

The fopen() function opens a handle to a file stream The syntax for the fopen() function is: open_file = open(“text file”, “mode”);

A file pointer is a special type of variable that refers to the currently selected line or character in a file

Table 6-1 Mode arguments of the fopen() function

$BowlersFile = fopen(“bowlers.txt”, “r+”);

Figure 6-1 Location of the file pointer when the fopen() function uses a mode argument of “r+”

$BowlersFile = fopen(“bowlers.txt”, “a+”);

Figure 6-2 Location of the file pointer when the fopen() function uses a mode argument of “a+”

Closing a File Stream

Use the fclose function when finished working with a file stream to save space in memory

$BowlersFile = fopen(“bowlers.txt”, “a”);

$NewBowler = “Gosselin, Don\n”;

fwrite($BowlersFile, $NewBowler);

fclose($BowlersFile);

Writing Data to Files

PHP supports two basic functions for writing data to text files: file_put_contents() function writes or

appends a text string to a file fwrite() function incrementally writes data to a

text file

Writing Data to Files

Escape sequences used to identify the end of a line: UNIX/Linux platforms use the \n carriage return Macintosh platforms use \r carriage return Windows uses both the \r carriage return escape

sequence and the \n newline escape sequence

Writing an Entire File

The file_put_contents() function writes or appends a text string to a file

The syntax for the file_put_contents() function is: file_put_contents (filename, string[, options])

file_put_contents() Function

$TournamentBowlers = “Blair, Dennis\n”;

$TournamentBowlers .= “Hernandez, Louis\n”;

$TournamentBowlers .= “Miller, Erica\n”;

$TournamentBowlers .= “Morinaga, Scott\n”;

$TournamentBowlers .= “Picard, Raymond\n”;

$BowlersFile = “bowlers.txt”;

file_put_contents($BowlersFile, $TournamentBowlers);

file_put_contents() Function

if (file_put_contents($BowlersFile, $TournamentBowlers) > 0)

echo “Data was successfully written to the

$BowlersFile file.”;

echo “No data was written to the $BowlersFile file.”;

If no data was written to the file, the function returns a value of 0

Use the return value to determine whether data was successfully written to the file

The FILE_USE_INCLUDE_PATH constant searches for the specified filename in the path that is assigned to the include_path directive in your php.ini configuration file

The FILE_APPEND constant appends data to any existing contents in the specified filename instead of overwriting it

Writing an Entire File<h1>Coast City Bowling Tournament</h1><?phpif (isset($_GET['first_name']) && isset($_GET['last_name'])) {

$BowlerFirst = $_GET['first_name'];$BowlerLast = $_GET['last_name'];$NewBowler = $BowlerLast . “, “ . “$BowlerFirst” . “\n”;$BowlersFile = “bowlers.txt”;if (file_put_contents($BowlersFile, $NewBowler, FILE_APPEND) > 0)

echo “{$_GET['first_name']} {$_GET['last_name']} has been registered for the bowling tournament!”;

elseecho “Registration error!”;

echo “To sign up for the bowling tournament, enter your first and last name and click the Register button.”;

?><form action=”BowlingTournament.php” method=”get”enctype=”application/x-www-form-urlencoded”>First Name: <input type=”text” name=”first_name” size=”30” />Last Name: <input type=”text” name=”last_name” size=”30” /><input type=”submit” value=”Register” /></form>

Figure 6-6 Bowling registration form

Handling Magic Quotes

Magic quotes automatically adds a backslash (\) to any: Single quote (') Double quote (”) NULL character contained in data that a user submits

to a PHP scriptMy best friend's nickname is “Bubba”

My best friend\'s nickname is \”Bubba\”

Handling Magic Quotes

Table 6-2 Magic quote directives

Disable magic quotes in your php.ini configuration file and instead manually escape the strings with the addslashes() function

addslashes() Function Accepts a single argument representing the text string

you want to escape and returns a string containing the escaped string

$Nickname = addslashes($_GET['nickname']);echo $Nickname; // My best friend\'s nickname is \”Bubba\”.

With magic quotes enabled:My best friend\\\'s nickname is \\\”Bubba\\\”

stripslashes() Function Removes slashes that were added with the addslashes() function

To prevent the display of escaped characters, use the stripslashes() function with the text you want to print

if (file_put_contents($BowlersFile, $NewBowler, FILE_APPEND) > 0)

echo “” . stripslashes($_GET['first_name']) . “ “

. stripslashes($_GET['last_name'])

. “ has been registered for the bowling tournament!”;

echo “Registration error!”;

stripslashes() Functionif (isset($_GET['first_name']) && isset($_GET['last_name'])) {

$BowlerFirst = addslashes($_GET['first_name']);$BowlerLast = addslashes($_GET['last_name']);$NewBowler = $BowlerLast . “, “ . “$BowlerFirst” . “\n”;$BowlersFile = “bowlers.txt”;if (file_put_contents($BowlersFile, $NewBowler, FILE_APPEND) >

0)echo “{$_GET['first_name']}{$_GET['last_name']} has been registered for the bowling

tournament!”;else

echo “Registration error!”;}else

echo “To sign up for the bowling tournament, enter your first

and last name and click the Register button.”;

stripslashes() Function

Figure 6-7 Output of text with escaped characters

Writing Data Incrementally

Use the fwrite() function to incrementally write data to a text file

The syntax for the fwrite() function is: fwrite($handle, data[, length]);

The fwrite() function returns the number of bytes that were written to the file

If no data was written to the file, the function returns a value of 0

Locking Files

To prevent multiple users from modifying a file simultaneously use the flock() function

The syntax for the flock() function is:

flock($handle, operation)

Table 6-3 Operational constants of the flock() function

Reading an Entire File

Table 6-4 PHP functions that read the entire contents of a text file

file_get_contents() Function

Reads the entire contents of a file into a string

$DailyForecast = “San Francisco daily weather

forecast: Today: Partly cloudy. Highs from the 60s to

mid 70s. West winds 5 to 15 mph. Tonight: Increasing clouds. Lows

in the mid 40s to lower 50s. West winds 5 to 10 mph.”;

file_put_contents(“sfweather.txt”, $DailyForecast);

$SFWeather = file_get_contents(“sfweather.txt”);

echo $SFWeather;

readfile() Function

Prints the contents of a text file along with the file size to a Web browser

readfile(“sfweather.txt”);

file() Function

Reads the entire contents of a file into an indexed array Automatically recognizes whether the lines in a text file

end in \n, \r, or \r\n$January = “48, 42, 68\n”;$January .= “48, 42, 69\n”;$January .= “49, 42, 69\n”;$January .= “49, 42, 61\n”;$January .= “49, 42, 65\n”;$January .= “49, 42, 62\n”;$January .= “49, 42, 62\n”;file_put_contents(“sfjanaverages.txt”, $January);

file() Function$JanuaryTemps = file(“sfjanaverages.txt”);

for ($i=0; $i<count($JanuaryTemps); ++$i) {

$CurDay = explode(“, “, $JanuaryTemps[$i]);

echo “Day “ . ($i + 1) . “ ”;

echo “High: {$CurDay[0]} ”;

echo “Low: {$CurDay[1]} ”;

echo “Mean: {$CurDay[2]}”;

file() Function

Figure 6-8 Output of individual lines in a text file

Reading Data Incrementally

Table 6-5 PHP functions that iterate through a text file

The fgets() function uses the file pointer to iterate through a text file

Reading Data Incrementally

You must use fopen() and fclose() with the functions listed in Table 6-5

Each time you call any of the functions in Table 6-5, the file pointer automatically moves to the next line in the text file (except for fgetc())

Each time you call the fgetc() function, the file pointer moves to the next character in the file

Reading Directories

Table 6-6 PHP directory functions

Reading Directories

To iterate through the entries in a directory, open a handle to the directory with the opendir() function

Use the readdir() function to return the file and directory names from the open directory

Use the closedir() function to close a directory handle

Reading Directories

$Dir = “C:\\PHP”;

$DirOpen = opendir($Dir);

while ($CurFile = readdir($DirOpen)) {

echo $CurFile . “ ”;

closedir($DirOpen);

scandir() Function

Returns an indexed array containing the names of files and directories in the specified directory

$Dir = “C:\\PHP”;

$DirEntries = scandir($Dir);

foreach ($DirEntries as $Entry)

echo $Entry . “ ”;

Creating Directories

The mkdir() function creates a new directory To create a new directory within the current directory:

Pass just the name of the directory you want to create to the mkdir() function

mkdir(“bowlers”);

To create a new directory in a location other than the current directory: Use a relative or an absolute path

mkdir(“..\\tournament”);

mkdir(“C:\\PHP\\utilities”);

Figure 6-9 Warning that appears if a directory already exists

Obtaining File and Directory Information

Table 6-7 PHP file and directory status functions

Obtaining File and Directory Information$DailyForecast = “San Francisco daily weather forecast: Today: Partly cloudy. Highs from the 60s to mid 70s. West winds 5 to 15 mph. Tonight: Increasing clouds. Lows in the mid 40s to lower 50s. West winds 5 to 10 mph.”;$WeatherFile = “sfweather.txt”;if (is_writable($WeatherFile)) {

file_put_contents($WeatherFile, $DailyForecast);echo “The forecast information has been saved to

the $WeatherFile file.”;}else

echo “The forecast information cannot be saved tothe $WeatherFile file.”;

Table 6-8 Common file and directory information functions

$Dir = “C:\\PHP”;if(is_dir($Dir)) {

echo “<table border='1‘ width='100%'>”;echo “<tr><th>Filename</th><th>File Size</th>

<th>File Type</th></tr>”;$DirEntries = scandir($Dir);foreach ($DirEntries as $Entry) {

echo “<tr><td>$Entry</td><td>” . filesize($Dir . “\\” . $Entry) . “</td><td>” . filetype($Dir . “\\”. $Entry) . “</td></tr>”;

}echo “</table>”;

echo “The directory does not exist.”;

Figure 6-10 Output of script with file and directory information functions

Copying and Moving Files

Use the copy() function to copy a file with PHP The function returns a value of true if it is successful or

false if it is not The syntax for the copy() function is:

copy(source, destination)

For the source and destination arguments: Include just the name of a file to make a copy in the

current directory, or Specify the entire path for each argument

Copying and Moving Files

if (file_exists(“sfweather.txt”)) {

if(is_dir(“history”)) {

if (copy(“sfweather.txt”,“history\\sfweather01-27-2006.txt”))

echo “File copied successfully.”;else

echo “Unable to copy the file!”; }

elseecho (“The directory does not exist!”);

echo (“The file does not exist!”);

Renaming Files and Directories

Use the rename() function to rename a file or directory with PHP

The rename() function returns a value of true if it is successful or false if it is not

The syntax for the rename() function is: rename(old_name, new_name)

Removing Files and Directories

Use the unlink() function to delete files and the rmdir() function to delete directories

Pass the name of a file to the unlink() function and the name of a directory to the rmdir() function

Both functions return a value of true if successful or false if not

Use the file_exists() function to determine whether a file or directory name exists before you attempt to delete it

Summary

The stream is used for accessing a resource, such as a file, that you can read from and write to

A handle is a special type of variable that PHP uses to represent a resource such as a file

The fopen() function opens a stream to a text file A file pointer is a special type of variable that refers to

the currently selected line or character in a file

Summary

Use the fclose() function to ensure that the file doesn’t keep taking up space in your computer’s memory

PHP supports two basic methods for writing data to text files: file_put_contents() and the fwrite() function

Magic quotes automatically add backslashes to any single quote, double quote, or NULL character contained in data that a user submits to a PHP script

Summary

PHP includes various functions, such as the fgets() function, that allow you to use the file pointer to iterate through a text file

To iterate through the entries in a directory, you open a handle to the directory with the opendir() function

PHP includes various file and directory status functions, such as the file_exists() function, which determines whether a file or directory exists

PHP Programming with MySQL Slide 6-1 CHAPTER 6 Working with Files and Directories.

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